High-performance red light-emitting diodes from quasi-two-dimensional perovskite nanocrystals

Metal halide perovskite light-emitting diodes offer a promising platform for low-cost full-color displays, yet achieving high-performance pure-red emission remains challenging. Here, we report a crystallization regulation strategy for mixed bromide/iodide quasi-two-dimensional perovskites using a multifunctional molecule, 4-(trifluoromethyl)benzenesulfonamide, which simultaneously coordinates with organic spacer cations, Pb²⁺ ions and halide ions. Moreover, the combination of large steric hindrance and ordered molecular assembly in the precursor solution plays a decisive role in directing the formation of nanocrystals, thereby suppressing defect formation, inhibiting halide ions migration, and enhancing exciton binding energy. The resulting light-emitting diodes exhibited pure-red emission at ~635 nm, delivering a peak external quantum efficiency of 30.2%, a maximum luminance exceeding 25,000 cd m^-2, and a half-lifetime of 8426 min. Achieving perovskite light-emitting diodes with performance comparable to that of quantum-dot or organic light-emitting diodes would mark a major milestone toward commercialization. This work would expand opportunities beyond conventional light-emitting diode technologies.